let canvas = document.createElement('canvas');
let ctx = canvas.getContext("2d");
var image = new Image();
image.onload = function() {
ctx.drawImage(image, 0, 0);
};
image.src = "data:image/png;base64,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";
document.querySelector('body').appendChild(canvas);
// There are no possible ways of doing this on client side but if you are
// using Node.js try:
let a = Buffer.from('JavaScript').toString('base64');
console.log(a);
let b = Buffer.from(a, 'base64').toString();
console.log(b);